Southern California Edison spokesman Gil Alexander said Thursday that the man, who is employed by a private contractor assigned to replace the reactor’s vessel head, "momentarily lost his balance" and fell into the pool Jan. 27 while leaning over to retrieve a flashlight.

“He was wearing all of the appropriate safety equipment, including a life preserver vest. We immediately began a thorough medical screening to determine if there had been any injury,” Alexander told The Times.

The pool is more than 20 feet deep and holds water that continually circulates through the reactor core.

Workers had previously removed the highly radioactive uranium fuel that normally sits at the bottom of the pool, officials said.

Edison may review its procedures for working around the reactor pool and may require that workers tie off with ropes to a surrounding structure as a way of preventing another incident, Alexander said.